Citizens United doesn’t enable companies to give to political campaigns. Not directly. It says that corporate persons may buy as much airtime as they can afford.
EDITOR: Correct. See below:
The Supreme Court held in Citizens United that it was unconstitutional to ban free speech through the limitation of independent communications by corporations, associations, and unions,[21] i.e. that corporations and labor unions may spend their own money to support or oppose political candidates through independent communications like television advertisements.[22] This ruling was frequently interpreted as permitting corporations and unions to donate to political campaigns,[23] or else removing limits on how much a donor can contribute to a campaign.[24] However, these claims are incorrect, as the ruling did not affect the 1907 Tillman Act’s ban on corporate campaign donations (as the Court noted explicitly in its decision[25]), nor the prohibition on foreign corporate donations to American campaigns,[26] nor did it concern campaign contribution limits.[27] The Citizens United decision did not disturb prohibitions on corporate contributions to candidates, and it did not address whether the government could regulate contributions to groups that make independent expenditures.[22] The Citizens United ruling did however remove the previous ban on corporations and organizations using their treasury funds for direct advocacy. These groups were freed to expressly endorse or call to vote for or against specific candidates, actions that were previously prohibited.[28] — Wikipedia
